Prokaryotic microbial diversity analysis and metabolic function prediction of salt lakes on the Qinghai-Tibet Plateau

The Dong Taijinar Salt Lake (DT) and Xi Taijinar Salt Lake (XT) have been widely studied as mineral-rich areas. However, little is known about the composition and distribution of the microbial communities in these two lakes. In this study, metagenomics sequencing was used to analyze the diversity and potential functions of the microbial communities in DT and XT. According to our report, the salinity of DT (332.18-358.30 g/L) was 10 times higher than that of XT (20.09-36.83 g/L). Interestingly, the dominant domain in DT was Archaea (96.16%), while that in XT was Bacteria (93.09%). The distribution of Bacteria in the DT revealed 33 phyla and 1717 genera. The dominant genus in DT was Marinobacillus, which was positively correlated with total phosphorus content. There were four main phyla and 153 genera identified in the Archaea of DT. The most abundant Archaea genera in DT were Natronomonas (24.61%) and Halorubrum (23.69%), which were mainly positively correlated with the Na+, Ca2+, and Cl- contents. Similarly, there were 33 phyla and 1906 genera of Bacteria in XT, and Loktanella was the dominant genus. The archaeal taxonomy in XT mainly included four phyla and 149 genera. Proteobacteria and Euryarchaeota were the most abundant bacterial and archaeal phyla in the two salt lakes. Analysis of the halophilic mechanisms of the microorganisms identified in these two salt lakes revealed that the Bacteria in XT preferred to synthesize compatible solutes, whereas the Archaea in DT preferred a "salt-in" adaptation strategy in salt-stressed environments. IMPORTANCEThe Qinghai-Tibet Plateau is the origin of many lakes and mountains in China. Among them, the Dong Taijinar and Xi Taijinar salt lakes are important biological resources with unknown microbial community compositions and functional potentials. The results of this study revealed significant differences in the distribution of Bacteria and Archaea between the two salt lakes. Salinity mainly drives lower biodiversity and restricted bacterial growth and metabolism in the high-salinity and near-saturated Dong Taijinar Salt Lake. This study not only identifies the key microorganisms in two penetrating salt lakes, but also provides insights into the mechanisms of salinity tolerance and the unknown ecological functions of microorganisms in extreme environments.